1. Field of the Invention
This invention relates to coffee brewing apparatus which allows a brew cycle to be initiated either manually or automatically at a preset time but which prevents a brew cycle from proceeding if a plurality of required operating conditions are not implemented.
2. Description of the Prior Art
Numerous efforts have been made over the years to automate coffee brewing apparatus intended for household use. These have often been of complex design utilizing costly components, subject to frequent breakdowns, and requiring frequent and expensive maintenance in order to keep them in operating condition. In a recent instance, U.S. Pat. No. 4,682,537 discloses a commercial vending machine which provides probes arranged at different levels for sensing the amount of brewed coffee remaining. When a tank containing the brewed coffee is approximately one-third full, a "coffee low" light is displayed and a new coffee making cycle may be initiated either automatically of manually.
Another construction for commercial purposes is disclosed in U.S. Pat. No. 4,621,571 which provides a plurality of satellite receptacle units for the storage and dispensing of hot coffee which can be filled from a central brewing unit. A safety switch assembly assures that a brewing cycle cannot be initiated unless the brew chamber is properly aligned to discharge into a correspondingly aligned empty satellite unit.
An automatic household coffee brewing machine is disclosed in U.S. Pat. No. 4,566,802 which is programmable to begin a brewing cycle at a predetermined time, but which assures that an unattended coffee maker is not repeatedly activated thereafter. Thus, after filling the coffee maker with water and ground coffee, the user must manually supply a cycle enable signal, for example, by toggling a switch.
Automatic beverage brewing apparatus is disclosed in U.S. Pat. Nos. 4,608,916, 4,406,217, and 4,468,406, each of which allows a user to choose a desired number of cups of coffee as well as its strength. In U.S. Pat. No. 4,608,916, a plurality of indicator lights indicate no coffee, no water, and used filter, but there is no provision for rendering the apparatus inoperative in the event any of the indicator lights are lighted. In U.S. Pat. No. 4,468,406, there is mentioned, but no disclosure, of a low-water shut-off mechanism and associated alarm.
In U.S. Pat. No. 4,484,515, a sophisticated commercial expresso coffee machine is disclosed which brews coffee pods placed in one or more extraction heads. It includes an electronic control system which operates all functions of the machine including maintaining careful monitoring and control of the water temperature and the volume of hot water delivered to each extraction head. The machine diagnoses itself for possible failures and depleted supplies by showing on a display in code the kind of failure or of needed supply, for example, coffee, water. Each step of an operation is controlled until completion and the machine proceeds to the next only upon confirmation of proper execution of the earlier step. In the absence of confirmation, subsequent operations are not performed. Instead, a digital code signal is displayed in the machine panel corresponding to the failure or depletion in the machine.
Manually initiated coffee brewing apparatus is disclosed in U.S. Pat. No. 4,012,481 which includes a mill mechanism and utilizes a heater circuit containing a cover switch and a pair of other switches which control the heater mechanism. If all switches are closed, once initiated, a brew cycle proceeds to conclusion. Otherwise the apparatus remains inoperative except to digitally display a difficulty, such as "LID", to indicate that the cover is open.
It was the intent of the inventors to improve on known systems of the type just noted. Specifically, it was their intent to provide coffee brewing apparatus incorporating modern features while utilizing a system exhibiting a simplified construction and operation resulting in its being less expensive to manufacture and maintain. These goals have been achieved by reason of the present invention.